Method and apparatus for production of color images

ABSTRACT

Apparatus and method for transferring a color image from an original document to a film or to an output paper. The apparatus involves the formation of the component monochromatic images containing selected color component information in a monochromatic toner particle image configuration. The separate images of the toner configurations are exposed onto a photosensitive film to reconstruct the original document. The component images can be formed on a clear material or, preferably, on a transparent colored material, the colored material serving to eliminate the need for a filter for each of the color component exposures needed to reconstruct the original image. In a second embodiment, the component images can be formed on transparent regions of electrostatic photoconducting drum. A suitable light source placed in the middle of the drum, can expose a film on a platten near the surface. Again the transparent photoconducting material of the drum can have a color in each of a plurality of predetermined sections to eliminate the need for filters during reconstruction of an image from component monochromatic images.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to the production of color images and,more particularly, to the use of a plurality of electrostatic imagesencoded with monochromatic information to form color images. Themonochromatic electrostatic images can be combined to produce acomposite color image on photo-sensitive film.

2. Discussion of the Related Art

It is known in the related art to utilize the xerographic process toproduce color images. The color images are typically decomposed intothree monochromatic images and (in some embodiments) a grey-scale image.The images are utilized in a predetermined sequence to subject an outputmatrix, such as a paper matrix, to the xerographic process. During eachxerographic operation, a different color toner, as well as black tonerwhen a grey-scale is utilized, is applied to the matrix. The color tonerparticles are affixed to the output matrix and, when fused, produce thecolor image.

The same type of process can be utilized to formulate transparencies orcolor image negatives. The basic technique of decomposition of theimages and reconstruction by means of colored, electrostatically,charged particles affixed to the output matrix is generally similar.However, complementary color images are used in production of negatives.The technique is generally complicated when a plurality of colored tonerparticles are fused together to form a color image. The difficulty ofmaintaining color integrity for the multiplicity of color combinationsand the difficulty of adequate fusing of the components compromise thequality. This compromise in quality is compounded by the number of tonertransfer stations required to supply the various color toner particlesto the electrostatic media.

A need has therefore been felt for apparatus and method to produce acolor image using the xerographic technique to provide aphoto-sensitive-type output media. The use of photo-sensitive-typematerials replacing a polychromatic output matrix generally eliminatesproblems involved in the deposition of an image into intermediateelectrostatically formed images composed of charged color particles andthe subsequent combination into a single color image.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide method andapparatus for an improved technique of production of color images.

It is another object of the present invention to provide method andapparatus for an improved color image production utilizing theelectrostatic processes to provide the intermediate images that are arepresentation of selected monochromatic information.

It is yet another object of the present invention to provide improvedapparatus and method for producing a color image that involvesdecomposition of an original color image into three monochromaticelectrostatic images and reconstructing the composite image by exposinga photo-sensitive film to the monochromatic images illuminated byradiation of the appropriate wavelength.

These and other objects are accomplished, according to the presentinvention, by providing a transparent matrix for receivingelectrostatically charged toner particles in an electrostatic copyapparatus. The transparent matrix is provided with a series ofmonochromatic images and the monochromatic images are transferred to astation where photo-sensitive film is exposed through thesemonochromatic images by means of radiation of a pre-selected wavelengthcorresponding to the color component that the monochromatic imagerepresents. The exposed film is then transferred to a developingapparatus and thereafter separated from the photosensitive matrix toprovide a color image.

These and other features of the invention will be understood uponreading of the following discussion along with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-section view of the apparatus for providinga color image according to the present invention.

FIG. 2 is a second embodiment for providing a color image according tothe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Detailed Description of theFigures

Referring now to FIG. 1, element 10 is an image input device for anelectrostatic image producing apparatus. The apparatus includes a plate11 for positioning an original document and a scanning apparatus 12 forencoding the information of the document into a form suitable foreventual application of the information to a charged photoconductingdrum 15. The drum 15 has a toner recovery apparatus 23b and a toner tray23a for respectively removing toner from the photoconducting drum 15 andfor applying a toner coating determined by an electrostatic chargestored on the drum. An electrostatic charge is applied to thephotoconducting drum 15 after the toner recovery has taken place atstation 23b. Information is imposed on the drum 15 by an opticalapparatus 25 that can be, for example, a laser scanning device. Theoptical apparatus 25 produces a pattern on the photoconducting drum byvarying the conductivity of the drum in a manner that is related to theoriginal document. The charged area of drum 15, passing through thetoner tray 23a, has toner particles attracted thereto in a manner thatreproduces an image. The drum 15 rotates the latent image charge so thatthe latent image charge comes in contact with a clear film 32, the film32 having the property that it is capable of maintaining anelectrostatic charge or in some manner retaining the latent image tonerparticles originally positioned on the drum 15. The clear film isunrolled from supply drum 31, passes through the electrostatic imagingapparatus and other apparatus and is stored on drum 33. The clear film32 moves past the drum 15 at the same linear speed as the toner surfaceof the drum and is constrained by pressure roller 14. The tonerparticles are transferred, at least in part, to the clear film 32. Theclear film 32, coated with toner particles, is then passed throughfusing elements 26. The fusing elements serve to affix the latent imagetoner pattern, initially formed on the drum 15 and transferred to theclear film 32, for transport to another location without distortion.Elements 27 are position sensors and serve ultimately to control theregistration of the clear film images when multiple images aretransferred. The clear film 32 is forced between rollers 37 and 44 atwhich time the clear film (with toner image) is brought intoregistration with the photo-sensitive film 43 that is provided fromroller 41. The photo-sensitive film 43 and the clear film 32 pass beforea suitable light source (either a continuous source or a flash-pulsedsource), 46 which exposes the photo-sensitive film through a patternresulting from the toner image stored on the clear film. For a multipleexposure process, i.e. in which a plurality of images contain theselected spectral information necessary to produce composite colorimages, film 43 is halted and a plurality of images from toner images onthe clear film 32 are exposed onto the photo-sensitive film 43. Theclear film then passes over roller 38 and is taken up on rewind roll 33.Meanwhile, the photo-sensitive film 43 continues to travel betweenpressure nip rollers 47. A supply roll 45 provides a suitable outputmedia to transfer the image from the photo-sensitive film to the outputmedia 49 itself. The photo-sensitive film is thereafter stored on rewindroller 42, while the output media is cut by apparatus 51 and eventuallythe finished copy on the output media 49 is stored in output tray 52.

Referring next to FIG. 2, an alternative arrangement for obtaining thesame image reconstruction is shown. Once again, the image is provided atstation 10 wherein an original document on plate 11 is subjected to anoptical scanning process by device 12. The result of the scanningprocess is the production of an image encoded with either optical orwith electronic information that can be reproduced by an opticalapparatus 25. The optical apparatus 25 is utilized after the tonerremoval stage 23b and prior to the application of toner to thephotoconducting material 21 on the drum. It will be clear to thosefamiliar with the art of electrostatic reproduction processes, thatbetween station 23b and the optical apparatus 25, an electrostaticcharge must be placed on the photoconductor drum. Once again, the imageis stored on the photoconductor drum 21 in the form of an electrostaticcharge pattern. However, in this case, the photoconductor coated drum 21is fabricated using a transparent material. Optical shielding, indicatedby element 24, is required for accurate image reproduction. Thephotoconductor drum 21 rotates carrying the electrostatic charge and theelectrostatic charge produces a latent image by attracting charged tonerparticles. A photo-sensitive film 63 supplied from a storage roller 61is positioned by a positioning roller 62 to be constrained to moveacross a platten 26. The constraint can be provided by tension on acurved surface or by a vacuum platten or by an electrostatic surfaceattraction. The platten 26, as well as the photoconducting drum 21, aretransparent and, when the light source 22 positioned at the interior ofthe drum is energized, the latent image formed by the toner particles onthe photoconducting material 21 is transferred to the photo-sensitivefilm 63. In the case of transfer of a multi-color image, the film 63 ishalted and multiple exposures are made, one exposure for each selectedcomposite color component. The film is then advanced past positioningroller 65 and forced between pressure nip rollers 47 at which point theoutput media 49 is pressed in contact with the photo-sensitive film andthe color image is transferred to the output media. The cutter 51 cutsthe output media 49 and the finished product is deposited in output tray52.

Operation of the Preferred Embodiment

The operation of the preferred embodiment depends on several importantfeatures. The xerographic apparatus is used to form separately amonochromatic image equivalent to a selected primary color component ofa composite color image on the photo-sensitive matrix. As is typical inthe reconstruction of photographic composite color images, three (oralternately four) color images will be required to expose the film andprovide a composite full color image. The process can be simplified whenthe translucent image storage film itself can have appropriate colorregions rather than being a neutral transparent color. Thus, when thelight source 46 is used to expose the subsequent monochromatic images,the color transparent matrix itself provides the light filteringfunctions, rendering the positioning of different filters before theexcitation light source unnecessary. Similarly, in the apparatusdisclosed in FIG. 2, the transparent photoconducting drum 21 can havemultiple color regions. When the photo-sensitive film matrix 63 ishalted, the photoconductor drum 21 is rotated into position and thelight source 22 is energized, the color of the photoconducting materialitself serving as the filter.

It will be clear that the process of transferring the image from thexerographic images to the output media 49 can be omitted and the exposedphoto-sensitive film itself can be developed and cut and used as afinished copy.

With respect to the film chemistry that would be used in the materialsdesignated by 43 or 63, the color dry silver paper, manufactured by theMinnesota Mining and Manufacturing Company a photo-sensitive materialsimilar to the micro-encapsulated imaging film, manufactured by the MeadImaging, Inc. division of Mead Corporation, or other similar color ormonochromatic imaging products can be used as the photo-sensitivematerial. With the negative acting micro encapsulated imaging films,regions are implanted in an appropriate matrix that, when not activatedby radiation of the appropriate wavelength, result in the correspondingcolor being produced and subsequently transferred to a second matrixwhen a second matrix is pressed with sufficient force against the firstmatrix. The pressure ruptures the micro encapsulated areas that have notbeen irradiated, causing color to be transferred to the second matrix inthese areas. The Mead micro-encapsulated film has the areas producingcolor deactivated by radiation of a wavelength different than thewavelengths of the produced color. The wavelength difference can beaccommodated by appropriate choice of filter parameters.

The Mead micro-encapsulated film material consists of a matrix of evenlydistributed microcapsules coated onto a substrate film and containingchemical substances that produce the primary colors of yellow, cyan, andmagenta when ruptured by mechanical pressure. Composite color images canbe reproduced by exposing the Mead film to three distinct wavelengths oflight through appropriate image masks, The microcapsules reopened tothis radiation by polymerizing into non-ruptible heads, leaving thenon-exposed microcapsules susceptable to rupture to release their colormaterial.

Finally, regular photographic films of the "instant" developing type mayalso be utilized as the photo-sensitive film (63 or 93). In this case,the pressure nip rollers (47) may be used to rupture and distribute theappropriate developer chemistry contained within the construction fromEastman Kodak Company or Polaroid Corporation could then be used andeliminate the need for a separate supply of output media (49) onto whichthe image must otherwise be transferred prior to output.

It will also be clear that for the 3M dry silver paper, the nip rollers47 will be replaced by heating rollers or similar means for the imagedevelopment.

It will be clear that in FIG. 2, the registration of the drum must beset quite precisely for sharp reconstruction of the images. With respectto the registration of the clear film of FIG. 1, the various colors ofthe portions of the translucent film, that provide the filtering action,can help provide for registration.

The transfer of the optical image from the imager 10 to the opticalsystem 25 can take a multiplicity of forms. Optical system 25 can, forexample, be a laser that scans the photoconducting surface of the drumresponse to an encoding by a scanner 12 in the original document entry.This laser control has the advantage that, although the document entryportion 10 is shown as associated with the apparatus, the optical entryapparatus can in fact, be at a distant location from the xerographicdevice and the laser scanning implementation of apparatus 25 can becontrolled by a transmitted signal. In addition, the xerograhic devicecould be configured to produce composite color hardcopy through digitalor analog communication of color or monochromatic image data from acomputer host, thus acting as a printing peripheral device. Scanner 12and optical apparatus 25 can, however, be implemented by a fiber opticsystem that in essence scans a moving segment of the original documentand transfers the scanned signal to the electrostatic charge on thephotoconducting drum. The fiber optic system requires the use of filtersto provide for component color images.

It will be clear that no significant difference in and principle canresult from the use of the negative color image components as opposed tothe positive color image components. The difference is important only inthe selection of primary color components.

Referring once again to the embodiment shown in FIG. 2, thephoto-sensitive film 63 and the surface containing the image are not incontact. Therefore, the light from flash lamp 22 must be collimated toprovide sharp images.

The above description is included to illustrate the operation of thepreferred embodiment and is not meant to limit the scope of theinvention. The scope of the invention is to be limited only by thefollowing claims. From the above discussion, many variations will beapparent to one skilled in the art that would yet be encompassed by thespirit and scope of the invention.

What is claimed is:
 1. Apparatus for producing a color image,comprising:a transparent material capable of storage of an image formedby an electrostatic process; an electrostatic machine for applying aplurality of electrostatic images to said transparent material;photo-sensitive material responsive to a light source, saidphoto-sensitive material is proximately adjacent to said transparentmaterial having electrostatic images formed thereon; and apparatus forexposing said photo-sensitive material to said plurality of images, eachof said plurality of images is superimposed on said photo-sensitivematerials by radiation of an appropriate spectral profile, saidphoto-sensitive material is a micro-encapsulated photo-sensitivematerial, said color image apparatus further including an outputmaterial and a transfer device for transferring an image from saidphoto-sensitive material activated by said superimposed images to saidoutput material, said transparent material is comprised of a pluralityof colored sections, said colored sections acting as filters that allowa preselected bandwidth or radiation to pass through while blockingother preselected bandwidths from passing to facilitate the utilizationof a single radiation source to produce a plurality of color images,said electrostatic machine includes said transparent material as part ofa rotatable drum, said plurality of electrostatic images being formed onsaid drum without being thermally fixed to said transparent material,said micro-encapsulated photo-sensitive material can be activated byradiation with a spectral content different from the spectral content ofa said color image.
 2. The color image producing apparatus of claim 1wherein said photo-sensitive material is developed to provide a finalimage.
 3. Apparatus for forming a color image, comprising:electrostaticimage means for providing at least one image formed by electrostatictechniques, said at least one image having a pre-selected spectralrelationship to said color image; photosensitive means; and exposure forexposing said at least one image on said photosensitive means, saidexposed area of said photosensitive means having a pre-establishedspatial position on said at least one image being exposed on saidphoto-sensitive means by radiation having spectral characteristics to bedetermined by said pre-selected spectral relationship, saidphoto-sensitive means includes a medium having micro-encapsulated colorregions, said apparatus further including means for transferring animage from said photo-sensitive means to said output medium, saidmicro-encapsulated color regions are activated by a radiation spectrumdifferent from a color spectrum of said color image.
 4. The apparatus ofclaim 3 wherein said predetermined spectral characteristic is providedby a medium upon which said at least one electrostatially formed imageis placed.
 5. The apparatus of claim 3 wherein said image formed byelectrostatic technique is formed on a transparent region of a drumassociated with said electrostatic image means, said exposure meansincluding a radiation source on the interior of said drum, saidphoto-sensitive means having a predetermined spatial relationship withsaid drum.
 6. The color image of claim 3 wherein said at least one imageis comprised of a plurality of images, each of said plurality of imageshave a pre-selected spectral characteristics relative to said colorimage, and wherein said exposed plurality of images are superimposed onsaid photo-sensitive means.
 7. The color image apparatus of claim 6wherein said electrostatically formed images are fused on anintermediate transparent medium, each of said electrostatically formedimages being stored on a region of said transparent intermediate mediumhaving color determined by said pre-selected spectral relationship. 8.The color image apparatus of claim 3 wherein said image formed by saidelectrostatic image means results from scanning a charged photoconductorby a laser beam.
 9. The color image apparatus of claim 3 wherein saidcolor image in a reproduction of an original color image, said at leastone image containing information pertaining to a preselected spectralprofile of said original color image.
 10. A method of producing a colorimage, comprising the steps of:forming a plurality of images by anelectrostatic imaging process, each of said plurality of imagesincluding information related to a predetermined spectralcharacteristics of said color image; exposing said plurality ofelectrostatically formed images onto a photo-sensitive medium, whereinsaid plurality of exposures are superimposed, radiation performing saidexposing step has a pre-established spectral characteristic; anddeveloping said superimposed plurality of images in said photo-sensitivemedium, said photosensitive medium is a micro-encapsulated material andsaid developing step includes transfer of an image from saidmicro-encapsulated material to an output material, said method ofproducing a color image further including the step of activating saidmicro-encapsulated material by a radiation spectrum different from theradiation spectrum of said color image.
 11. The method of producing acolor image of claim 10 wherein said forming step includes the step offorming each electrostatic image on a medium having a selected color,wherein said selected color is determined by said pre-establishedspectral transmission characteristics.
 12. The method of producing acolor image of claim 10 wherein said forming step includes the step offorming each of said plurality of images on the transparent surface of adrum in the apparatus forming said electrostatic image.